You've Just Seen Your Last Blackout

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How to build a portable power station.By Jeffrey R. Yago, PE.

Less than 30 years ago, a power outage would be little more than a minor inconvenience to most people. Today, with the proliferation of home-business computers as well as answering and fax machines, a prolonged power interruption can bring your livelihood to a halt. Large cities are served by more than one electrical transmission line and most power outages usually last only as long as it takes to bypass a downed line, but country dwellers might well be stranded for days.

The most commercially available solution is a backup power supply system, but these stand-alone units (those in the $200 to $500 price range) will only keep a personal computer operating long enough to allow you to quickly save information and shut down. Not a terribly versatile solution.

This project will allow you to be prepared for the next short term power outage and maintain an almost normal life style while waiting for the line power return. The station cannot power everything in your home, but it will run a computer and fax machine, or television and VCR for up to six hours, and lighting for several rooms at the same time ...and can be built for a total cost of less than $400.

The system is designed to be stored out of the way until needed, then serve as your first line of defense in an emergency. You can also extend the power stations usefulness: load it in the car and take it on your next camping trip, or use it to power small tools or lights at the job site when a generator is not practical.

SYSTEM DESCRIPTION

The power station has been designed around a battery charger, a deep discharge battery, and a DC to AC inverter, all mounted in an easy to build wooden cabinet. Each component has been carefully matched in performance to provide a very efficient system in a very small package.

We have chosen a deep discharge 12 volt, 850 cranking amp capacity, lead-acid marine battery. Although two 6 volt golf cart batteries wired in series will provide much better long term performance, the marine battery is sealed and is much safer to handle and keep charged in a confined space. Since this is the heart of the system, buy a quality battery rated for extended deep discharge use. A standard automobile battery will not provide satisfactory operating time and will fail completely after several deep discharge cycles.